When you're ready to let the past go completely through forgiveness, I think you'll find that the other person's willingness to accept their part in a relationship breakdown, is irrelevant.
Myself, I was molested by a close family friend throughout my childhood, and for the longest time I thought I wouldn't be able to forgive him until he apologized. (I doubt he's capable of admitting anything.) However, by chosing to forgive him, it was as though I erased all the changes his actions had made in me. I refused to be a victim any longer. I refused to carry an open wound in my heart. I acknowledged that people commit evil acts, but chose not to let my ability to love, appreciate my children, think clearly (plus all other negative effects of the abuse) be affected by him any longer. It was amazing: I got myself back. When you are ready to stop holding on to any resentment, you can do the same.
Your line, "Maybe I just want to help her through this time, but she won't make the step of seeing errors" really jumped out at me. People can only process their desire to change on their own. To want to help her with that seems rather controlling/codependent/authoritarian--more like proving yourself right than actually helping your stbxw. As Al Turtle points out, people always make sense to themselves at the time. Whether she will one day stop seeing her past actions as still making sense is ultimately up to her.
It's good that you can see the blessing in how things turned out, and can appreciate how hard you tried. Best of luck on your journey towards peace.
